1. Field of the Invention
The present invention relates to a mobile communication system, and particularly, to an apparatus and a method for searching signals transmitted from neighboring base stations.
2. Background of the Related Art
Generally, international mobile telecommunication-2000 (IMT-2000) can be divided into a synchronous code division multiple access (CDMA) method and an asynchronous CDMA method. These are being standardized by the third generation partnership project 2 (3GPP2) centering around U.S.A. and by third generation partnership project (3GPP), centering around Korea, Europe and Japan, respectively.
The synchronous CDMA method synchronizes cells with the help of a device which tracks absolute time, such as a global positioning system (GPS). The asynchronous CDMA method does not need to synchronize cells.
In the radio environment, when a terminal searches a cell, there are two kinds of searching. The first is an initial cell search, and the second is a neighboring cell search. In an initial cell search, the terminal searches for a base station (cell) from which service will be provided when the terminal is turned on. In a neighboring cell search, the terminal searches cells around the present cell after obtaining information from the present cell through the initial cell search. Information about neighboring cells is always needed for mobile service, including during hand-over.
In neighboring cell searching, the terminal may or may not receive information about the neighboring cells, such as location information, scrambling code, etc. from the present cell. If the terminal is able to acquire this information about the neighboring cells, it is easy for the terminal to search the neighboring cells. However, it is difficult for the terminal to search the neighboring cells if this information is not acquired.
Therefore, an apparatus is needed which will search the neighboring cells easily, regardless of what information is acquired by the terminal. Also, an apparatus is required which is able to search the neighboring cells using a simple hardware device without applying an excessive software load on the terminal.